I wanted to say something about the best ROM, gaming ROM.

To explain, Android has its own ‘layers’.

Kernel is the bottom layer. It actually contacts with the hardware like CPU, camera and such. Then there are HALs (Hardware Abstraction Layer). It’s the interface between the kernel and android native executables. Then there is native executables of android, like dex2oat, dalvikvm. Lastly there is Android runtime, the virtual JVM to support android apps which are written on Kotlin/Java.

What I want to say is that JVM can’t have optimizations. JVM runs Java bytecode which is not like binary that can be optimized with LTO/-O3 flag etc. The actual performance increase may be gained by putting LTO/-O3 (optimization flags) to app_process(32/64) or dalvikvm etc. native executables. But I’ve never seen any ROM putting those flags on their source neither that will make a big difference. So all roms will have similar performance with same android version. NO Gaming ROM.

Also, the best ROM may vary by person. For example, I don’t like Lineage OS’s derivative UI and app (my personal opinion) but I like Derpfest’s and other. But there will be someone here that likes lineage more than derp etc. There are much more things for consideration if this ROM is good or not. Testing a rom for some mins won’t kill you. NO Best ROM.

Oh, I forgot that why custom rom, mostly AOSP based rom is faster than original rom or stock is because of simplicity of AOSP itself. It doesn’t mean it doesn’t have a bloatware, tracking app or anything. It just means that AOSP is so simple that it need more code to supply many feature since it just a barebones. And this result can vary depending on how device tree is made or how a person is built the rom. So again, NO Best ROM, NO Gaming ROM, NO custom rom is better than stock ROM.